Higher perceived stress in caregivers leads to more wheesing in infants
Higher perceived stress in caregivers (mostly mothers) of 2- to 3-month-old infants who had a genetic predisposition to asthma and allergy was associated with an increased risk of more wheezing during the first 14 months of life, according to researchers. Investigators recruited 496 children (263 males and 233 females) from a Boston hospital within 48 hours of delivery. Of the 496 children, 287 (57.9 percent) never wheezed within the 14 months, 116 (23.4 percent) had one reported wheezing episode, 47 (9.5 percent) had two, 28 (5.6 percent) suffered three, and 18 (3.6 percent) had four attacks. In the study, white persons reported lower levels of stress than did Hispanics. As household income increased, perceived stress levels decreased. Divorced and single caregivers showed higher stress levels than did those who were married. The highest stress scores were reported by caregivers whose infants were either in the bottom or top quartile in birth weight. Also, children were more likely to wheeze if they had mothers (but not fathers) with active asthma. In addition, repeated wheeze was associated with the presence of higher levels of cockroach antigen in the house. The study appears in the first issue for February of the American Thoracic Society’s peer-reviewed American Journal of Respiratory and Critical Care Medicine.
Model of potent German cockroach allergen developed
Allergic reactions to a potent German cockroach allergen, which can result in emergency room visits for asthma in sensitive children, are not linked to enzymatic activity as dust mite allergens have shown. This potent cockroach allergen elicits immunoglobulin E (IgE) responses in 60 to 80 percent of allergic patients even at very low levels in the environment. In asthma, many allergic reactions involve antibodies of the IgE class. (Cockroach allergen exposure is strongly linked to asthma attacks among susceptible children living in inner cities.) The investigators developed a molecular model of the cockroach allergen, Bla g 2, but found no association between enzymatic activity and allergenicity. The “enzyme hypothesis” for allergic reaction was originally developed to explain why dust mite allergens are so strongly associated with the development of allergic responses. They note that most dust mite allergens are enzymes, hence the theory. The authors’ data showed that, although Bla g 2 lacks enzymatic activity, it is a potent allergen, inducing IgE responses at exposure levels that are often one to two orders of magnitude lower than that from dust mite allergens. They believe that other genetic and environmental factors are important determinants of sensitization from German cockroach allergen. The research appears in the first issue for February of the American Thoracic Society’s peer-reviewed American Journal of Respiratory and Critical Care Medicine.
A new test for allergic airway inflammation
According to an editorial in the first issue for February of the American Thoracic Society peer- reviewed journal, adenosine 5'-monophosphate (AMP) may provide a more discriminating bronchoconstrictive stimulus for allergic asthma than does the currently used direct stimuli tests methacholine and histamine. Stephen T. Holgate, M.D., of Southampton General Hospital, Southampton, United Kingdom, comments that a study by Gea de Meer, M.D., in the current American Journal of Respiratory and Critical Care Medicine shows that airway response to inhaled AMP more closely reflects allergic inflammatory responses in the lower airways when compared with those produced by methacholine. A central hallmark of asthma is nonspecific bronchial hyperresponsiveness (BHR). One of the most prominent underlying factors related to the expression of BHR is ongoing inflammatory processes in the airway wall. Histamine and methacholine are the most commonly used trigger tests to mimic BHR. In his study, Dr. de Meer investigated the association between markers of airway inflammation and BHR to the tests AMP and methacholine in 230 largely asymptomatic young adults. The researchers concluded that AMP responsiveness appears to relate to the allergic mechanisms of airway obstruction while methacholine responsiveness is more directed toward diminished airway diameter. In his editorial, Dr. Holgate notes that a European Respiratory Workshop Report has included the AMP challenge as “one worthy of serious further consideration” as a more discriminating test for specific forms of airway inflammation linked to asthmatic phenotype (that caused by genetic makeup and environmental factors).
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Journal
American Journal of Respiratory and Critical Care Medicine